Chapter 12 Review

How many possible 3-base codons can there be?

64

What is the function of mRNA?

Carries copies of the instructions for assembling amino acids from DNA to the rest of the cell.

What occurs during the process of replication?

Cell duplicates DNA in copying process.

T or F: All amino acids are specified by only one codon.

False

T or F: Chromosomal mutations result from changes in a single gene.

False

T or F: Operons are frequently found in eukaryotes.

False

T or F: RNA editing occurs in the cytoplasm of the cell.

False

True or False: According to the principle of base pairing, hydrogen bonds could form only between adenine and cytosine.

False

True or False: In eukaryotic chromosomes, DNA replication begins at a single point in the chromosome and proceeds in 2 directions.

False

True or False: The nucleotide must be joined together in a specific order.

False

What occurs during the process of translation?

The cell uses information from mRNA to produce proteins.

Why are individual chromosomes visible only during mitosis?

The chromatin fibers are tightly packed.

Match the roles with the molecules: DNA or RNA 1. master plan 2. goes to the ribosomes in the cytoplasm 3. blueprint 4. remains in the nucleus

1. DNA 2. RNA 3. RNA 4. DNA

Eukaryotic promoters are usually found just ____ the TATA box, and they consist of a series of short _____ sequences.

1. before 2. DNA

What is true about translation? (3)

1. before translation occurs, mRNA is transcribed from DNA in the nucleus. 2. It is the job of tRNA to bring the proper aa into the ribosome to be attached to the growing peptide chain. 3. when the ribosome reaches a stop codon, it releases the newly formed polypeptide and the mRNA molecule.

What is true about hox genes?

1. in fruit flies, a mutation affecting the hox genes can replace a fly's antennae with a pair of legs. 2. The function of the hox genes in humans seems to be almost the same as it is in fruit flies.

Many RNA molecules from eukaryotic genes have selections called, _____, edited out of them before they become functional. The remaining pieces called, ____, are spliced together.

1. introns 2. exons

What is true about gene regulation in prokaryotic genes.

1. many other genes are regulated by repressor proteins. 2. some genes are regulated by proteins that enhance the rate of translated by proteins that enhance the rate of transcription.

What is true about gene mutations?

1. point mutations that involve the insertion or deletion of a nucleotide change the reading frame of the genetic message. 2. frameshift mutations affect every aa that follows the point of the mutation.

During DNA replication, the DNA molecule 1. _____, or unzips, into 2 strands. Each strand serves as a 2.____, or model to produce the new strands. Two new 3.______ strands are produced, following the rules of 4. ______.

1. separates 2. template 3. complementary 4. base pairing

What is an operon?

A group of genes that operate together.

Base-pairing: TACGTT

ATGCAA

What is the codon that serves as the "start" codon for protein synthesis?

AUG

Where is DNA located in prokaryotic cells?

Cytoplasm

Where does RNA polymerase bind?

DNA promoters

How can only 4 bases in RNA carry instructions for 20 different amino acids?

Each AA is coded by 3 letters (a codon)- 64 possible codons.

What occurs when a molecule of DNA is "unzipped"?

Hydrogen bonds between the bases are broken.

How does the repressor protein prevent transcription?

It binds to the DNA preventing the RNA polymerase from transcribing it.

What is a codon?

It consists of three consecutive nucleotides that specify a single amino acid that is to be added to a polypeptide.

What is the function of ribosomal RNA?

Makes up ribosomes

Inversions

Part of a chromosome becomes oriented in the reverse of its usual direction.

What is true about transcription?

RNA polymerase uses one strand of DNA as a template to assemble nucleotides into a strand of RNA.

The sites where DNA replication and separation occur are called ______.

Replication forks

Where does translation take place?

Ribosomes

T or F: Each DNA molecule resulting from replication has one original strand and one new strand.

True

Eukaryotic chromosomes contain both DNA and protein, packed together to form ______.

chromatin

What role do the hox genes play in the development of an organism?

differentiation of cells and tissues in the embryo.

Many proteins are ____, which catalyze and regulate chemical reactions.

enzymes

Duplication

extra copies of one or more chromosome

Mutations that cause dramatic changes in protein structure are often ____.

harmful

What is the function of the TATA box?

helps position the RNA polymerase by marking the point at which transcription begins.

Eukaryotic DNA is generally located in the cell _____ in the form of a number of chromosomes.

nucleus

Deletion

one or more nucleotides is deleted from the DNA sequence.

Adenine, Guanine, Cytosine, and Thymine are four kinds of _________ bases in DNA.

pair

Translocation

part of a chromosome breaks off and attaches to another.

Mutations are a source of _______ in a species.

genetic variation

What is an anticodon?

3 tRNA bases that are complementary to the mRNA (codon)

What is true about chromosome structure?

A human cell contains more than 1 meter of DNA.

A mutation involving the insertion or deletion of a nucleotide is a _____ mutation.

frameshift

What is the function of tRNA?

Transfers each amino acid to the ribosome to help assemble proteins.

T or F: The actions of DNA-binding proteins help to determine whether a gene is turned on or off.

True

True or False: Adenine and guanine are larger molecules than cytosine and thymine because they have two rings in their structure.

True

True or False: Changes in chromatin structure and histone-DNA binding are associated with changes in gene activity.

True

True or False: Most prokaryotes contain a single, circular DNA molecule.

True

What is the makeup of a nucleotide?

a 5-carbon sugar called deoxyribose, a phosphate group, and a nitrogenous (nitrogen-containing) base

What are histones?

a protein molecule around which DNA is tightly coiled in chromatin.

What do nucleosomes do?

a. They fold enormous lengths of DNA into the cell nucleus. b. They help regulate how genes are "read" to make proteins.

List the 3 main differences between DNA and RNA.

a. ribose in place of deoxyribose- DNA b. RNA is single stranded c. RNA contains Uracil in place of Thymine

Proteins are made by joining ____ into long chains called polypeptides.

amino acids

Mutations that occur at a single point in the DNA sequence are ___ mutations.

point

What job are most RNA molecules involved with?

protein synthesis

What forms the backbone of a DNA chain?

sugar and phosphates

What is polyploidy?

the condition of having extra sets of chromosomes.